Worked fine.

Couldn’t seem to get add_editor_styles() working in my theme and I didn’t have time to mess around with it. This plugin did the job perfectly for me.

I would comment that the author should make the wording a little more clear though. I thought “Style” meant the actual CSS, not the name of the style. It’d also be nice if you could see your style in the editor itself to visualise the classes things have.